(College of Electromechanical Engineering, Qingdao University of Science and Technology, Qingdao 266061, China)

 Abstract: Aiming at the problem of poor dynamic performance indicators of time delay system in response process, control method of the first order inertia lag link was researched.Classical adjustment methods of controller parameters were compared and summarized. An iterative feedback adjustment algorithm based on the structure of the PID controller was put forward. The controlled object and the PID controller were used as the forward channel transfer function of system block diagram. PID controller parameter setting value was obtained by the input and output data of closed loop system as well as the linear quadratic Gaussian criterion. This optimization method was compared with Ziegler Nichols (ZN) regulation, internal model control (IMC) method and error square integral method (ISE) under the condition of the same noise. The results indicate that the IFT method can shorten adjustment time , reduce overshoot and improve robustness. Therefore, the design method is meaningful for improving response effect of time delay system.

 Key words: lagging system; iterative feedback tuning(IFT); PID; Matlab/Simulink